Interface circuits are generally in the form of integrated circuit chips, which are disposed between a data providing circuit, such as, for example, a personal computer (PC) and a peripheral driver provide parallel-to-serial and serial-to-parallel data conversion. Interface circuits can be incorporated into the communication port of a more complex integrated circuit chip. Communication interface circuits generally include an oscillator and a crystal to synchronize data conversion with a fairly precise oscillator frequency, which facilitates asynchronous communications. The purpose for having a crystal controlled oscillator is to ensure that the frequency of a specific device is within a defined limit specified for the device operation. The use of an on-chip free-running oscillator, built entirely of integrated components, e.g. transistors, resistors, capacitors, inductors, etc., but no crystal, will typically not be acceptable due to temperature drift, manufacturing tolerances, supply voltage variation, etc. On the other hand, crystals are typically external devices, thus requiring a more complex external assembly.